Rotary Steering with Multiple Contact Points

ABSTRACT

A system in which a drill string is disposed within a wellbore that extends from a wellsite surface to a subterranean formation. At least three rotary steerable system (RSS) modules are collectively coupled in series between the drill string and a drill bit. Each RSS module includes at least three steering pads spaced circumferentially apart around a perimeter of the RSS module, and a valve operable to sequentially actuate the steering pads. The system also includes a controller operable to independently actuate the valve of each RSS module simultaneously.

BACKGROUND OF THE DISCLOSURE

Oil and gas wellbore drilling applications may utilize a rotary steerable system to control the direction of drilling during formation of the wellbore. A rotary steerable system may utilize a drill bit that is coupled with a drill collar and rotated to drill through the subterranean formation. One or more valves and control systems may control steering pads selectively actuated for radial deflection to control the direction of drilling. Such valves may be held at angular orientations with respect to the rotating drill collar to control the flow of fluid to the steering pads. However, such systems may not accurately control the direction of drilling, and may be limited with regard to a maximum rate of changing of the drilling direction.

SUMMARY OF THE DISCLOSURE

The present disclosure introduces a system for drilling a wellbore. The system includes a rotary steerable system (RSS) coupled between a drill string collar and a drill bit. The RSS includes first, second, and third sections. The first section includes three first steering pads and a first valve operable to sequentially actuate the first steering pads. The second section includes three second steering pads and a second valve operable to sequentially actuate the second steering pads. The third section includes three third steering pads and a third valve operable to sequentially actuate the third steering pads.

The present disclosure also introduces an apparatus that includes a drill string disposed within a wellbore that extends from a wellsite surface to a subterranean formation. The apparatus also includes a drill bit and three rotary steerable system (RSS) modules collectively coupled in series between the drill string and the drill bit. Each RSS module includes three steering pads spaced circumferentially apart around a perimeter of the RSS module, a valve operable to sequentially actuate the steering pads, and a controller operable to independently actuate the valve of each RSS module simultaneously.

The present disclosure also introduces a method comprising conveying apparatus within a wellbore that extends from a wellsite surface to a subterranean formation, wherein the apparatus includes a drill string, a drill bit, and at least three rotary steerable system (RSS) modules collectively coupled in series between the drill string and the drill bit. Each RSS module includes: three steering pads spaced circumferentially apart around a perimeter of the RSS module; and a valve operable to sequentially actuate the steering pads. The controller is operated to independently actuate the valve of each RSS module to, simultaneously: sequentially actuate the steering pads of a first one of the RSS modules to operatively urge the first one of the RSS modules in a first azimuthal direction; sequentially actuate the steering pads of a second one of the RSS modules to operatively urge the second one of the RSS modules in a second azimuthal direction substantially different from the first azimuthal direction; and sequentially actuate the steering pads of a third one of the RSS modules to operatively urge the third one of the RSS modules in a third azimuthal direction substantially different from the second azimuthal direction.

These and additional aspects of the present disclosure are set forth in the description that follows, and/or may be learned by a person having ordinary skill in the art by reading the materials herein and/or practicing the principles described herein. At least some aspects of the present disclosure may be achieved via means recited in the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a schematic view of at least a portion of apparatus according to one or more aspects of the present disclosure.

FIG. 2 is a schematic view of at least a portion of apparatus according to one or more aspects of the present disclosure.

FIG. 3 is a perspective view of at least a portion of apparatus according to one or more aspects of the present disclosure.

FIG. 4 is a schematic view of at least a portion of apparatus according to one or more aspects of the present disclosure.

FIG. 5 is a schematic view of at least a portion of apparatus according to one or more aspects of the present disclosure.

FIG. 6 is a schematic view of at least a portion of apparatus according to one or more aspects of the present disclosure.

FIG. 7 is a schematic view of at least a portion of apparatus according to one or more aspects of the present disclosure.

FIG. 8 is a schematic view of at least a portion of apparatus according to one or more aspects of the present disclosure.

FIG. 9 is a flow-chart diagram of at least a portion of a method according to one or more aspects of the present disclosure.

FIG. 10 is a schematic view of at least a portion of apparatus according to one or more aspects of the present disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for simplicity and clarity, and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact.

FIG. 1 is a schematic view of at least a portion of a drilling system 20 according to one or more aspects of the present disclosure. The drilling system 20 may comprise a bottom hole assembly (BHA) 22, which may be part of or coupled to a drill string 24 utilized to form a wellbore 26 via direction drilling. The drilling system 20 comprises a rotary steerable system (RSS) 28 comprising at least three sets of laterally movable steering pads 30. Each steering pad 30 of a set may be at substantially the same axial position within the RSS 28. Each set of steering pads 30 is axially offset along a longitudinal axis of the RSS 28, and may be controlled by and/or in conjunction with a corresponding valve system 32. Each steering pad 30 may be designed to act against a corresponding, perhaps pivotable component of the RSS 28, and/or against the surrounding wall of the wellbore 26, thereby providing directional control. The valve systems 32 may each be positioned with the corresponding set of steering pads 30 within a drill collar of the RSS 28. The drill collar and/or other housing 35 of the lowermost (in a downhole direction) set of steering pads 30 is directly or indirectly coupled with a drill bit 36, which is rotated to cut through a surrounding rock formation 38 that may be in a hydrocarbon bearing reservoir 40.

Depending on the environment and the operational parameters of the drilling operation, the drilling system 20 may comprise a variety of other features. For example, the drill string 24 may comprise additional drill collars 42 incorporating various drilling modules, such as logging-while-drilling (LWD) and/or measurement-while-drilling (MWD) modules 44, among others.

Various surface systems also may form a part of or otherwise be utilized in conjunction with the drilling system 20. For example, a drilling rig 46 positioned above the wellbore 26 may be utilized in conjunction with a drilling fluid system 48 also positioned at the wellsite. The drilling fluid system 48 is operable to deliver drilling fluid (e.g., “mud”) 50 from a drilling fluid tank 52, through tubing 54, and into the drill string 24. The drilling fluid 50 returns to the wellsite surface 10 through an annulus 56 between the drill string 24 and the surrounding wall of the wellbore 26. The return flow may be utilized to remove drill cuttings resulting from operation of drill bit 36. The drilling fluid 50 may also be utilized in conjunction with control of the RSS 28 and the steering pads 30. That is, in addition to being conducted by an internal passage of the drill string 24 to the drill bit 36, the drilling fluid 50 may also be directed to or otherwise utilized to actuate the steering pads 30. Such actuation may be controlled by the corresponding valve systems 32, thereby controlling the drilling direction.

The drilling system 20 may also comprise or otherwise be utilized in conjunction with a surface control system 58. The surface control system 58 may be utilized to control communication with the RSS 28. For example, the surface control system 58 may receive data from downhole sensor systems and communicates commands to the RSS 28 to control actuation of the valve systems 32 and thus the drilling direction. Such control electronics and/or other control apparatus may also or instead be located downhole, perhaps integral to the RSS 28, such as may operate in conjunction with an orientation sensor to control the drilling direction. The downhole control electronics may be operable to communicate with the surface control system 58, such as to receive directional commands and/or to relay information related to drilling and/or the formation 38 to the surface control system 58.

The RSS 28 may be conveyed and operated within the wellbore 26 via the drill string 24, as described above. The RSS 28 may also or instead be utilized in conjunction with a mud motor and/or turbine, including as described below and/or otherwise within the scope of the present disclosure. Other means of conveyance and/or operating fluid delivery, however, may also be utilized in implementations within the scope of the present disclosure, such as coiled tubing, casing, and/or other tubular means.

FIG. 2 is a schematic view of at least a portion of an example implementation of the RSS 28 according to one or more aspects of the present disclosure. FIG. 2 more clearly depicts how the RSS 28 may comprise a first section 12, a second section 13, and a third section 14, coupled together in series. Each section 12-14 may be a module, sub, sub-assembly, portion, and/or other type of section assembled into and/or otherwise partially forming the RSS 28. Also, although not depicted in FIG. 2, flexible and/or other intervening components may be coupled between ones of the RSS sections 12-14.

Referring to FIGS. 1 and 2, collectively, the drill bit 36 may be mounted to the housing 35 of the lowermost (in a downhole direction) RSS section 14. A housing 34 of the uppermost (in an uphole direction) RSS section 12 may comprise or be coupled to an uphole connector (not shown) of the RSS 28, such as may be operable to couple the RSS 28 to an adjacent drill collar and/or other component of the drill string 24. A housing 37 of the intermediate RSS section 13 may be coupled to or otherwise between the housing 34 of the upper RSS section 12 and the housing 35 of the lower RSS section 14. Such coupling of the upper housing 34, the intermediate housing 37, and the lower housing 35, in series, may be via industry-standard fittings (such as box-pin connections), threaded engagement, and/or other means. Also, as described above, such coupling may be in conjunction with one or more flexible components. That is, the RSS sections 12-14 may be directly coupled to each, or they may be indirectly coupled to each other via one or more flexible and/or other intervening components. One or more of the RSS sections 12-14 may also comprise one or more flexible components, such as may provide a greater degree of bending or rotation between neighboring ones of the RSS sections 12-14. The RSS sections 12-14, the flexible components, and/or other intervening components may be modular, such as may provide a degree of interchangeability.

A variety of RSS components are carried within internal passages 62 of the housings 34, 35, and 37, such as may be operable for actuation of the steering pads 30 mounted to the corresponding housings 34, 35, and 37. In the example implementation(s) described below, each steering pad 30 may be moved radially outward from the corresponding housing 34, 35, or 37 by a corresponding piston 64, which may be hydraulically actuated via drilling fluid 50 metered by the corresponding valve system 32. However, each piston 64 may extend a sufficient distance from the corresponding housing 34, 35, or 37 so as to contact the sidewall of the wellbore, instead of urging the steering pad 30 into contact with the sidewall of the wellbore. Accordingly, reference herein to the steering pads 30 being actuated for intermittent contact with the sidewall of the wellbore is deemed to include implementations lacking actual steering pads and instead comprising an actuator and/or other device (e.g., the piston 64) operable to intermittently contact the sidewall of the wellbore, and which may hereafter be referred to herein as steering members. Moreover, hydraulic oil and/or other fluids carried internally with the RSS 28 and/or another component of the BHA or drill string may also or instead be utilized to activate the steering pads 30, pistons 64, and/or similarly functioning apparatus.

Each valve system 32 may comprise a rotational, spider, barrel, digital, and/or other type of valve 66. Each valve 66 may be selectively rotated, digitally actuated, and/or otherwise actuated to direct a portion of the drilling fluid 50 from the corresponding internal passage 62 to selected ones of the steering pads 30. For example, one or more hydraulic lines 68 may communicate drilling fluid 50 from the corresponding valve 66 to act against the pistons 64 corresponding to the steering pads 30. The housings 34, 35, and 37 and the drill bit 36 rotate during drilling of the wellbore 26, during which time each valve 66 may undergo a controlled, relative rotation to selectively deliver the drilling fluid 50 through the corresponding hydraulic line(s) 68 to the corresponding steering pads 30.

With each valve system 32, the valve 66 may be coupled to or otherwise driven by a shaft 70, which may be rotated by a corresponding electric and/or other type of motor 72. One or more encoders and/or other sensors 74 may be operatively engaged with the shaft 70 to monitor the angular orientation of each valve 66 relative to the corresponding housing 34, 35, or 37. Each valve system 32, or other component of the RSS 28, may also comprise one or more control devices 75, such as may comprise and/or operate in conjunction with a microprocessor and/or other controller 76. The control devices 75 and/or controllers 76 may each receive data from the corresponding sensors 74 and utilize such data and/or other data to control the corresponding motor 72. Each motor 72 may thus be operable in controlling the angular positioning of the corresponding valve 66. One or more of the control devices 75 and/or controllers 76 may also communicate with the surface control system 58, such as to receive commands and/or relay data. One or more of the control devices 75 and/or controllers 76 may also comprise and/or operate in conjunction with one or more additional components, such as a direction and inclination package containing magnetometers and accelerometers (not shown).

Operational power may be provided to each control device 75, controller 76, motor 72, and/or other components of the RSS 28 via one or more power sources, such as may be or comprise batteries and/or a turbine 80. Each turbine 80 may comprise and/or operate in conjunction with an alternator 82 driven by rotation of the turbine 80, such rotation being in response to the pressurized flow of the drilling fluid 50 through the internal passages 62.

One or more components of each valve system 32 and/or other component of the RSS 28 may be mounted within a pressure housing 86, such as may provide a level of protection against the relatively high pressure of the drilling fluid 50 and/or the rigors of the downhole environment. For example, the motors 72, encoders 74, control devices 75, controllers 76, and alternators 82 may be disposed within corresponding pressure housings 86 associated with each RSS section 12-14. Each pressure housing 86 may be rigidly attached to the corresponding housing 34, 35, and 37 via one or more centralizers and/or other members 88 disposed within the corresponding housing 34, 35, or 37. Thus, each pressure housing 86 may rotate with the corresponding housing 34, 35, or 37.

Each valve system 32 may comprise a valve 66, one or more hydraulic lines 68, a shaft 70, a motor 72, one or more sensors 74, a control device 75, a controller 76, a turbine 80 and/or other power source, an alternator 82, a pressure housing 86, combinations thereof, and/or other components. Two or more of the RSS sections 12-14, however, may share one or more components of the valves systems 32. For example, a single control device 75 and/or controller 76 may be operable to control the valves 66 of two or more of the RSS sections 12-14.

Each RSS section 12-14 comprises at least three steering pads 30. Each steering pad 30 of a set may be at substantially the same axial position relative to the corresponding RSS section 12-14. Thus, the steering pads 30 of the upper RSS section 12 may each be positioned at a first axial position relative to the RSS 28, the steering pads 30 of the intermediate RSS section 13 may each be positioned at a second axial position relative to the RSS 28, and the steering pads 30 of the lower RSS section 14 may each be positioned at a third axial position relative to the RSS 28, wherein the first, second, and third axial positions are axially offset from one another along the length of the RSS 28.

Each steering pad 30 may be activated by differential pressure, such as between the inside and outside of the corresponding housing 34, 35, or 37. When a steering pad 30 is activated, it pivots away from the RSS 28, ultimately pushing against the sidewall of the wellbore 26, thus deflecting the corresponding RSS section 12-14 in the opposite direction, thereby providing the RSS 28 with steering capability. As the housings 34, 35, and 37 rotate (substantially simultaneously), each valve 66 selectively operates to cause the extension and retraction of the corresponding steering pads 30 by alternatingly permitting and restricting the flow of drilling fluid 50 through the corresponding hydraulic line 68 to the corresponding piston 64 behind the steering pad 30. The steering pads 30 may thus rotate substantially simultaneously with the bit rotation speed. However, in other implementations within the scope of the present disclosure, substantially non-rotating pads may be utilized.

FIG. 3 is an exploded view of an example implementation of at least a portion of one of the valves 66. The valve 66 comprises a valve opening 90 that is rotated via operation of the motor 72. The valve opening 90 may be selectively aligned with selected ports 92 that are part of and/or rotate with the corresponding housing 34, 35, or 37. The ports 92 deliver drilling fluid 50 into hydraulic lines 68 for subsequent communication to the corresponding steering pads 30. In the example implementation depicted in FIGS. 1-3, each housing 34, 35, and 37 comprises three ports 92 connected to three steering pads 30 via hydraulic lines 68, although other implementations within the scope of the present disclosure may include ports 92 and/or steering pads 30 in other numbers.

The valve opening 90 may be selectively aligned with individual ports 92 or combinations of adjacent ports 92. Each valve 66 is selectively rotated via the shaft 70 and the motor 72 to bring the valve opening 90 into alignment or out of alignment with a selected one or two ports 92.

FIG. 4 is a sectional view of the steering pads 30 carried by the upper housing 34, the valve 66, and the related components. To facilitate an understanding of the angular relationship of the valve opening 90 with respect to the ports 92, the ports 92 have been labeled as first (1), second (2), and third (3) ports 92, corresponding with first (1), second (2), and third (3) steering pads 30. The first (1), second (2), and third (3) ports 92 and steering pads 30 are illustrated as positioned substantially at 0°, 120°, and 240°, respectively, around the housing 34. If the valve 66 and the housing 34 are both positioned at 0°, then the first (1) port 92 is activated by the pressure of drilling fluid 50, but the second and third ports are not activated. If the angle of the housing 34 is substantially 0° while the angle of the valve 66 is substantially 60°, then the first (1) and second (2) ports 92 are both activated.

The size of the valve opening 90 and each of the ports 92 may vary according to a variety of design parameters. For example, the valve opening 90 may have an angular width of about 90° and each of the ports 92 may have an angular width of about 80°. However, the angular widths and/or other dimensions of the valve opening 90 and the ports 92 may vary within the scope of the present disclosure. The number of openings 90, ports 92, and hydraulic lines 68 may also vary within the scope of the present disclosure, such as in accord with the number of steering pads 30 of a corresponding RSS section 12-14 (which may also vary within the scope of the present disclosure).

FIG. 5 is a simplified sectional view of the RSS 28 shown in FIGS. 1-4, in which the valve systems 32 and hydraulic lines 68 are simplified for clarity of the following description. The RSS 28 is at least indirectly coupled between a collar 110 of the drill string 24 and the drill bit 36. As described above, the RSS 28 comprises a first section 12, a second section 13, and a third section 14, where each RSS section 12-14 comprises at least three steering pads 30 and a valve system 32 operable to sequentially actuate the steering pads 30. In the example implementation depicted in FIG. 5, each RSS section 12-14 comprise two diametrically opposed steering pads 30. However, other implementations within the scope of the present disclosure may not comprise diametrically opposed steering pads 30.

The example RSS 28 depicted in FIG. 5 also comprises a controller 130 operable to control each of the valve systems 32. The controller 130 may comprise one or more instances of the control devices 75 and/or controllers 76 shown in FIG. 2. The controller 130 may be a single, discrete controller operable to control each of the valve systems 32, such that control/data lines 132 may extend between the controller 130 and the valves 66. Other implementations within the scope of the present disclosure, however, may utilize multiple controllers 130 each operable to control a corresponding one of the valve systems 32. Where multiple controllers are utilized, two or more (or each) of the controllers may be operably connected to a common communication bus, such that steering pad 30 activations may occur synchronously. The common or “main” controller may be located somewhere else in the BHA, such as in an MWD tool. One or more of the controllers may also be operable to communicate with other tools of the BHA, such as formation testing tools of MWD and/or LWD modules, via a common communication bus. For example, for closed-loop geosteering, the steering pad controllers may operable in conjunction with formation data obtained by an LWD of the BHA, such as to reference a formation feature that may utilized to guide steering. Thus, among other possible implementations, the LWD module may be utilized to obtain formation image data that may then be utilized with the steering pad controllers to maintain the drilling path within a pay-zone of the formation while elongating the wellbore.

The steering pad and/or other downhole controllers of the RSS 28 and/or other portions of the BHA may communicate with surface equipment (e.g., the surface control system 58 in FIG. 1) in substantially real-time manner. For example, such communication may be via wired drill pipe, electromagnetic (EM) telemetry, and/or others. However, mud pulse telemetry is also contemplated.

FIG. 6 is a schematic exterior view of the RSS 28 shown in FIG. 5 after the controller 130 has operably controlled the valve systems 32 to, simultaneously: sequentially actuate the steering pads 30 of the upper RSS section 12 to urge the upper RSS section 12 in a first azimuthal direction 140 relative to a longitudinal axis 160 of the wellbore 26; sequentially actuate the steering pads 30 of the middle RSS section 13 to urge the middle RSS section 13 in a second azimuthal direction 150 relative to the longitudinal axis 160 of the wellbore 26; and sequentially actuate the steering pads 30 the lower RSS section 14 to operatively urge the lower RSS section 14 in the first azimuthal direction 140 relative to a longitudinal axis 160 of the wellbore 26. That is, a first steering pad of the upper RSS section 12, indicated in FIG. 6 as steering pad 170, has been actuated and is thus pushing against the sidewall of the wellbore 26, thereby urging the upper RSS section 12 in the first azimuthal direction 140. However, a second steering pad of the upper RSS section 12, indicated in FIG. 6 as steering pad 180, has not been actuated and thus remains substantially retracted against the housing 34 of the upper RSS section 12, thereby permitting the upper RSS section 12 to travel in the first azimuthal direction 140. Simultaneously, a first steering pad of the intermediate RSS section 13, indicated in FIG. 6 as steering pad 171, has been actuated and is thus pushing against the sidewall of the wellbore 26, thereby urging the intermediate RSS section 13 in the second azimuthal direction 150. However, a second steering pad of the intermediate RSS section 13, indicated in FIG. 6 as steering pad 181, has not been actuated and thus remains substantially retracted against the housing 37 of the intermediate RSS section 13, thereby permitting the intermediate RSS section 13 to travel in the second azimuthal direction 150. Also simultaneously, a first steering pad of the lower RSS section 14, indicated in FIG. 6 as steering pad 172, has been actuated and is thus pushing against the sidewall of the wellbore 26, thereby urging the lower RSS section 14 in the first azimuthal direction 140. However, a second steering pad of the lower RSS section 14, indicated in FIG. 6 as steering pad 182, has not been actuated and thus remains substantially retracted against the housing 35 of the lower RSS section 14, thereby permitting the lower RSS section 14 to travel in the first azimuthal direction 140.

The second azimuthal direction 150 may be substantially opposite the first azimuthal direction 140. For example, the first and second azimuthal directions 140 and 150, respectively, may be angularly offset by an amount ranging between about 175 degrees and about 185 degrees. Such implementations may permit a dogleg of the wellbore 26 to be as high as about twenty degrees per 100 feet (or about twenty degrees per about 30.5 meters), although other values are also within the scope of the present disclosure. For example, referring to FIG. 1, the example wellbore 26 may change in direction by a dogleg angle 27 ranging up to about twenty degrees over a length 29 of the wellbore 26 that may be about 100 feet long, as measured along the longitudinal axis 160 of the wellbore 26.

Of course, other control schemes are also within the scope of the present disclosure. In general, the steering pads of each RSS section 12-14 may be controlled independently of the steering pads of each other RSS section 12-14, such that each RSS section 12-14 may be urged in a mutually different azimuthal direction.

Another example control scheme by which the steering pads of the individual RSS sections 12-14 may be controlled by the controller 130 is depicted in FIG. 7, in which the controller 130 has operably controlled the valve systems 32 to, simultaneously: simultaneously actuate each of the steering pads 30 of the upper RSS section 12 to centralize the upper RSS section 12 in the wellbore 26; simultaneously actuate each of the steering pads 30 of the intermediate RSS section 13 to centralize the intermediate RSS section 13 in the wellbore 26; and sequentially actuate the steering pads 30 the lower RSS section 14 to operatively urge the lower RSS section 14 in a steering direction 165 relative to a longitudinal axis 160 of the wellbore 26. That is, each steering pad 30 of the upper RSS section 12 has been actuated and is thus pushing against the sidewall of the wellbore 26, thereby urging the upper RSS section 12 towards the longitudinal axis 160 of the wellbore 26. Simultaneously, each steering pad 30 of the intermediate RSS section 13 has been actuated and is thus pushing against the sidewall of the wellbore 26, thereby urging the intermediate RSS section 13 towards the longitudinal axis 160 of the wellbore 26. Also simultaneously, a first steering pad of the lower RSS section 14, indicated in FIG. 7 as steering pad 191, has been actuated and is thus pushing against the sidewall of the wellbore 26, thereby urging the lower RSS section 14 in the steering direction 165. However, a second steering pad of the lower RSS section 14, indicated in FIG. 7 as steering pad 192, has not been actuated and thus remains substantially retracted against the housing 35 of the lower RSS section 14, thereby permitting the lower RSS section 14 to be azimuthally deflected and thereby point in the steering direction 165.

Another example control scheme (not shown) may be utilized to achieve a substantially neutral drilling tendency wherein each steering pad 30 of each RSS section 12-14 is simultaneously activated. For example, in such implementations utilizing rotary valves, the valves may be disengaged (such as by axial motion away from the openings leading to the steering pads 130), thus allowing drilling or other working fluid to simultaneously actuate each steering pad 30 associated with that valve. Similarly, in implementations utilizing digital valves, they may be digitally operated to simultaneously actuate each steering pad 30.

FIG. 8 is a side view of the RSS 28 shown in FIGS. 5-7 and demonstrating that one or more flexible components may be formed with or otherwise coupled between the RSS sections 12-14. For example, a flexible component 210 may be coupled between the upper RSS section 12 and the adjacent component 110 of the drill string 24 (see FIG. 1). Another flexible component 211 may be coupled between the upper RSS section 12 and the intermediate RSS section 13. Another flexible component 212 may be coupled between the intermediate RSS section 13 and the lower RSS section 14. One or more of the flexible components 210-212 may be or comprise a universal joint and/or other joint permitting relative bending between neighboring RSS sections 12-14 and the drill string component 110 while transferring rotary motion across the joint. One or more of the flexible components 210-212 may also or instead be or comprise a flex-sub, bent-sub, and/or other components operable to permit relative bending of RSS sections 12-14 during rotation.

The steerable system shown in FIGS. 1-8, described above, and/or otherwise within the scope of the present disclosure may be operable to counter the tendency of previous steering systems to buckle in response to excessive weight-on-bit. A steerable system according to one or more aspects of the present disclosure may also aid in ensuring that the steering pads furthest from the drill bit (i.e., in an uphole direction) contact the sidewalls of the wellbore, and as such may be utilized instead of or in addition to the upper stabilizer of a conventional RSS BHA. A steerable system according to one or more aspects of the present disclosure may also aid in dampening vibrations caused by drilling operations, such as by utilizing the upper and/or intermediary (relative to the drill bit, in an uphole direction) set of steering pads to press against the sidewalls of the wellbore, while maintaining an intended drilling direction.

FIG. 9 is a flow-chart diagram of at least a portion of a method (900) according to one or more aspects of the present disclosure. The method (900) may be executed utilizing at least a portion of the apparatus shown in one or more of FIGS. 1-8, among other apparatus within the scope of the present disclosure. For example, the method (900) may comprise conveying such apparatus within a wellbore that extends from a wellsite surface to a subterranean formation, wherein the wellbore may be substantially similar to the wellbore 26 shown in one or more of FIGS. 1, 6, and 7. Such apparatus may comprise or be utilized in conjunction with a drill string, a drill bit, and at least three RSS modules and/or other sections collectively coupled in series between the drill string and the drill bit, such as the drill string 24, the drill bit 36, and the RSS sections 12-14 shown in one or more of FIGS. 1, 2, and 5-8. The method (900) may comprise coupling (910) the RSS sections between the drill string and the drill bit, which may include coupling (915) one or more flexible components between ones of the RSS sections. As described above, each RSS section may comprise at least three steering pads spaced circumferentially apart around a perimeter of the RSS section, and a rotational valve operable to sequentially actuate the steering pads. The steering pads 30 may be substantially similar to those shown in one or more of FIGS. 1, 2, and 4-8, and the rotational valve may be substantially similar to at least a portion of the valve systems 32 shown in one or more of FIGS. 1-8.

The method (900) comprises operating (920) a controller to independently actuate the rotational valve of each RSS section. The controller may be substantially similar to the control devices 75, controllers 76, and/or controller 130 shown in one or more of FIGS. 2 and 5. Such operation (920) of the controller may comprise simultaneously: actuating the steering pads of a first one of the RSS modules sequentially to operatively urge (922) a first RSS section in a first azimuthal direction (such as the azimuthal direction 140 shown in FIG. 6); actuating the steering pads of a second one of the RSS modules sequentially to operatively urge (924) a second RSS section in a second azimuthal direction substantially different from the first azimuthal direction (such as the azimuthal direction 150 shown in FIG. 6); and actuating the steering pads of a third RSS section sequentially to operatively urge (926) a third RSS section in a third azimuthal direction substantially different from the second azimuthal direction. The second azimuthal direction may be substantially opposite the first azimuthal direction, and the third azimuthal direction may be substantially similar to the first azimuthal direction. For example, the first and third azimuthal directions may each be angularly offset from the second azimuthal direction by an amount ranging between about 175 degrees and about 185 degrees.

The method (900) may further comprise operating (930) the controller to control the rotational valves of the RSS modules to, simultaneously: actuate the steering pads of the first RSS section to operatively centralize (932) the first RSS section within the wellbore; actuate the steering pads of the second RSS section to operatively centralize (934) the second RSS section within the wellbore; and sequentially actuate the steering pads of the third RSS section to steer (936) the RSS with the third RSS section by urging the third RSS section in an azimuthal direction away from a longitudinal axis of the first and second RSS modules.

FIG. 10 is a schematic view of at least a portion of apparatus according to one or more aspects of the present disclosure. The apparatus is or comprises a processing system 1300 that may execute example machine-readable instructions to implement at least a portion of one or more of the methods and/or processes described herein, and/or to implement a portion of one or more of the example RSS sections and/or other downhole tools described herein. The processing system 1300 may be or comprise, for example, one or more processors, controllers, special-purpose computing devices, servers, personal computers, personal digital assistant (“PDA”) devices, smartphones, internet appliances, and/or other types of computing devices. Moreover, while it is possible that the entirety of the processing system 1300 shown in FIG. 10 is implemented within downhole apparatus, perhaps as at least a portion of the control devices 75, controllers 76, controller 130, other downhole apparatus shown in one or more of FIGS. 1-8, and/or other downhole apparatus, it is also contemplated that one or more components or functions of the processing system 1300 may be implemented in wellsite surface equipment, perhaps including the surface control system 58 depicted in FIG. 1 and/or other surface equipment.

The processing system 1300 may comprise a processor 1312 such as, for example, a general-purpose programmable processor. The processor 1312 may comprise a local memory 1314, and may execute coded instructions 1332 present in the local memory 1314 and/or another memory device. The processor 1312 may execute, among other things, machine-readable instructions or programs to implement the methods and/or processes described herein. The programs stored in the local memory 1314 may include program instructions or computer program code that, when executed by an associated processor, enable surface equipment and/or downhole controller and/or control system to perform tasks as described herein. The processor 1312 may be, comprise, or be implemented by one or a plurality of processors of various types suitable to the local application environment, and may include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (“DSPs”), field-programmable gate arrays (“FPGAs”), application-specific integrated circuits (“ASICs”), and processors based on a multi-core processor architecture, as non-limiting examples. Of course, other processors from other families are also appropriate.

The processor 1312 may be in communication with a main memory, such as may include a volatile memory 1318 and a non-volatile memory 1320, perhaps via a bus 1322 and/or other communication means. The volatile memory 1318 may be, comprise, or be implemented by random access memory (RAM), static random access memory (SRAM), synchronous dynamic random access memory (SDRAM), dynamic random access memory (DRAM), RAMBUS dynamic random access memory (RDRAM) and/or other types of random access memory devices. The non-volatile memory 1320 may be, comprise, or be implemented by read-only memory, flash memory and/or other types of memory devices. One or more memory controllers (not shown) may control access to the volatile memory 1318 and/or the non-volatile memory 1320.

The processing system 1300 may also comprise an interface circuit 1324. The interface circuit 1324 may be, comprise, or be implemented by various types of standard interfaces, such as an Ethernet interface, a universal serial bus (USB), a third generation input/output (3GIO) interface, a wireless interface, and/or a cellular interface, among others. The interface circuit 1324 may also comprise a graphics driver card. The interface circuit 1324 may also comprise a communication device such as a modem or network interface card to facilitate exchange of data with external computing devices via a network (e.g., Ethernet connection, digital subscriber line (“DSL”), telephone line, coaxial cable, cellular telephone system, satellite, etc.).

One or more input devices 1326 may be connected to the interface circuit 1324. The input device(s) 1326 may permit a user to enter data and commands into the processor 1312. The input device(s) 1326 may be, comprise, or be implemented by, for example, a keyboard, a mouse, a touchscreen, a track-pad, a trackball, an isopoint, and/or a voice recognition system, among others.

One or more output devices 1328 may also be connected to the interface circuit 1324. The output devices 1328 may be, comprise, or be implemented by, for example, display devices (e.g., a liquid crystal display or cathode ray tube display (CRT), among others), printers, and/or speakers, among others.

The processing system 1300 may also comprise one or more mass storage devices 1330 for storing machine-readable instructions and data. Examples of such mass storage devices 1330 include floppy disk drives, hard drive disks, compact disk (CD) drives, and digital versatile disk (DVD) drives, among others. The coded instructions 1332 may be stored in the mass storage device 1330, the volatile memory 1318, the non-volatile memory 1320, the local memory 1314, and/or on a removable storage medium 1334, such as a CD or DVD. Thus, the modules and/or other components of the processing system 1300 may be implemented in accordance with hardware (embodied in one or more chips including an integrated circuit such as an application specific integrated circuit), or may be implemented as software or firmware for execution by a processor. In particular, in the case of firmware or software, the embodiment can be provided as a computer program product including a computer readable medium or storage structure embodying computer program code (i.e., software or firmware) thereon for execution by the processor.

In view of the description above, the claims below, and each of the figures, collectively, a person having ordinary skill in the art will readily recognize that the present disclosure introduces a system for drilling a wellbore comprising: a rotary steerable system (RSS) at least indirectly coupled between a drill string collar and a drill bit, wherein the RSS comprises: a first section comprising at least three first steering members (e.g., actuators and/or pads) and a first valve operable to sequentially actuate the first steering members; a second section comprising at least three second steering members and a second valve operable to sequentially actuate the second steering members; and a third section comprising at least three third steering members and a third valve operable to sequentially actuate the third steering members.

The first valve may be a first rotational valve, the second valve may be a second rotational valve, and the third valve may be a third rotational valve. The first valve may be a first digital valve, the second valve may be a second digital valve, and the third valve may be a third digital valve.

The RSS may comprise a controller operable to control the first, second, and third valves. The controller may be operable to control the first, second, and third valves to, simultaneously: sequentially actuate the first steering members to operatively urge the first section in a first azimuthal direction; sequentially actuate the second steering members to operatively urge the second section in a second azimuthal direction substantially different from the first azimuthal direction; and sequentially actuate the third steering members to operatively urge the third section in a third azimuthal direction substantially different from the second azimuthal direction. The second azimuthal direction may be substantially opposite the first azimuthal direction, and the third azimuthal direction may be substantially similar to the first azimuthal direction. The first and third azimuthal directions may each be angularly offset from the second azimuthal direction by an amount ranging between about 175 degrees and about 185 degrees. The controller may be further operable to control the first, second, and third valves to, simultaneously: actuate the first steering members to operatively centralize the first section within the wellbore; actuate the second steering members to operatively centralize the second section within the wellbore; and sequentially actuate the third steering members to operatively urge the third section away from a longitudinal axis of the first and second sections.

The RSS may comprise: a first flexible component flexibly coupling the first and second sections; and a second flexible component flexibly coupling the second and third sections.

The RSS may comprise: a first joint disposed between the first and second sections; and a second joint disposed between the second and third sections. The first joint may be directly coupled to at least one of the first and second sections, and the second joint may be directly coupled to at least one of the second and third sections.

The at least three first steering members may be spaced circumferentially apart at a first axial position, the at least three second steering members may be spaced circumferentially apart at a second axial position that may be axially offset from the first axial position, and the at least three third steering members may be spaced circumferentially apart at a third axial position that may be axially offset from the first and second axial positions.

The RSS and drill bit may be operable to extend a wellbore with a dogleg of up to twenty degrees per 100 feet (30.5 meters).

The present disclosure also introduces an apparatus comprising: a drill string disposed within a wellbore that extends from a wellsite surface to a subterranean formation; a drill bit; at least three rotary steerable system (RSS) modules collectively coupled in series between the drill string and the drill bit, wherein each RSS module comprises: at least three steering pads (and/or actuators and/or other steering members) spaced circumferentially apart around a perimeter of the RSS module; and a valve operable to sequentially actuate the steering pads; and a controller operable to independently actuate the valve of each RSS module simultaneously. The at least three movable steering pads of each RSS module may be disposed at substantially the same axial position.

The valve may be operable to sequentially actuate the steering pads by sequentially directing fluid to actuators each associated with a corresponding one of the steering pads. The fluid directed to the actuators may be received from equipment disposed at the wellsite surface. The fluid directed to the actuators may be hydraulic oil carried in an internal chamber of the drill string.

Each RSS module may comprise: an uphole interface; a downhole interface; and a central portion comprising the at least three steering pads and the valve. The uphole interface may be a pin-end of a first box-pin coupling, and the downhole interface may be a box-end of a second box-pin coupling. Each RSS module may comprise a flexible portion coupled between the central portion and one of the uphole and downhole interfaces. The flexible portion may comprise a joint. The joint may be a universal joint. Each RSS module may comprise a passageway fluidly connecting the uphole and downhole interfaces.

The controller may be operable to actuate the valves of the RSS modules to, simultaneously: sequentially actuate the steering pads of a first one of the RSS modules to operatively urge the first one of the RSS modules in a first azimuthal direction; sequentially actuate the steering pads of a second one of the RSS modules to operatively urge the second one of the RSS modules in a second azimuthal direction substantially different from the first azimuthal direction; and sequentially actuate the steering pads of a third one of the RSS modules to operatively urge the third one of the RSS modules in a third azimuthal direction substantially different from the second azimuthal direction. The second azimuthal direction may be substantially opposite the first azimuthal direction, and the third azimuthal direction may be substantially similar to the first azimuthal direction. The first and third azimuthal directions may be each angularly offset from the second azimuthal direction by an amount ranging between about 175 degrees and about 185 degrees. The controller may be further operable to control the valves of the RSS modules to, simultaneously: actuate the steering pads of the first one of the RSS modules to operatively centralize the first one of the RSS modules within the wellbore; actuate the steering pads of the second one of the RSS modules to operatively centralize the second one of the RSS modules within the wellbore; and sequentially actuate the steering pads of the third one of the RSS modules to operatively urge the third one of the RSS modules away from a longitudinal axis of the first and second ones of the RSS modules.

The apparatus may further comprise: a first flexible component flexibly coupling first and second ones of the RSS modules; and a second flexible component flexibly coupling the second one of the RSS modules and a third one of the RSS modules. The apparatus may further comprise: a first joint disposed between first and second ones of the RSS modules; and a second joint disposed between the second one of the RSS modules and a third one of the RSS modules. The first joint may be directly coupled to at least one of the first and second ones of the RSS modules, and the second joint may be directly coupled to at least one of the second and third ones of the RSS modules.

The drill bit, the at least three RSS modules, and the controller may be collectively operable to extend the wellbore with a dogleg of up to twenty degrees per 100 feet (30.5 meters).

The present disclosure also introduces a method comprising: conveying apparatus within a wellbore that extends from a wellsite surface to a subterranean formation, wherein the apparatus comprises a drill string, a drill bit, and at least three rotary steerable system (RSS) modules collectively coupled in series between the drill string and the drill bit, and wherein each RSS module comprises: at least three steering pads (and/or other steering members) spaced circumferentially apart around a perimeter of the RSS module; and a valve operable to sequentially actuate the steering pads; and operating a controller to independently actuate the valve of each RSS module to, simultaneously: sequentially actuate the steering pads of a first one of the RSS modules to operatively urge the first one of the RSS modules in a first azimuthal direction; sequentially actuate the steering pads of a second one of the RSS modules to operatively urge the second one of the RSS modules in a second azimuthal direction substantially different from the first azimuthal direction; and sequentially actuate the steering pads of a third one of the RSS modules to operatively urge the third one of the RSS modules in a third azimuthal direction substantially different from the second azimuthal direction.

The second azimuthal direction may be substantially opposite the first azimuthal direction, and the third azimuthal direction may be substantially similar to the first azimuthal direction. The first and third azimuthal directions may each be angularly offset from the second azimuthal direction by an amount ranging between about 175 degrees and about 185 degrees.

The method may further comprise operating the controller to control the valves of the RSS modules to, simultaneously: actuate the steering pads of the first one of the RSS modules to operatively centralize the first one of the RSS modules within the wellbore; actuate the steering pads of the second one of the RSS modules to operatively centralize the second one of the RSS modules within the wellbore; and sequentially actuate the steering pads of the third one of the RSS modules to operatively urge the third one of the RSS modules in an azimuthal direction away from a longitudinal axis of the first and second ones of the RSS modules.

The method may further comprise, prior to conveying at least a portion of the apparatus within the wellbore, coupling the RSS modules in series between the drill string and the drill bit.

The method may further comprise, prior to conveying at least a portion of the apparatus within the wellbore: coupling a first flexible component between first and second ones of the RSS modules; and coupling a second flexible component between the second one of the RSS modules and a third one of the RSS modules. Each of the first and second components may comprise a joint.

Operating the controller may comprise operating the controller while rotating the drill bit to extend the wellbore at a dogleg of up to about twenty degrees per 100 feet (30.5 meters).

The foregoing outlines features of several embodiments so that a person having ordinary skill in the art may better understand the aspects of the present disclosure. A person having ordinary skill in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. A person having ordinary skill in the art should also realize that such equivalent constructions do not depart from the scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.

The Abstract at the end of this disclosure is provided to comply with 37 C.F.R. §1.72(b) to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 

What is claimed is:
 1. A system for drilling a wellbore, comprising: a rotary steerable system (RSS) at least indirectly coupled between a drill string collar and a drill bit, wherein the RSS comprises: a first section comprising at least three first steering members and a first valve operable to sequentially actuate the first steering members; a second section comprising at least three second steering members and a second valve operable to sequentially actuate the second steering members; and a third section comprising at least three third steering members and a third valve operable to sequentially actuate the third steering members.
 2. The system of claim 1 wherein the RSS further comprises a controller operable to control the first, second, and third valves to, simultaneously: sequentially actuate the first steering members to operatively urge the first section in a first azimuthal direction; sequentially actuate the second steering members to operatively urge the second section in a second azimuthal direction substantially different from the first azimuthal direction; and sequentially actuate the third steering members to operatively urge the third section in a third azimuthal direction substantially different from the second azimuthal direction.
 3. The system of claim 2 wherein the controller is further operable to control the first, second, and third valves to, simultaneously: actuate the first steering members to operatively centralize the first section within the wellbore; actuate the second steering members to operatively centralize the second section within the wellbore; and sequentially actuate the third steering members to operatively urge the third section away from a longitudinal axis of the first and second sections.
 4. The system of claim 1 wherein the RSS comprises: a first flexible component flexibly coupling the first and second sections; and a second flexible component flexibly coupling the second and third sections.
 5. The system of claim 1 wherein the RSS comprises: a first joint disposed between the first and second sections; and a second joint disposed between the second and third sections.
 6. An apparatus, comprising: a drill string disposed within a wellbore that extends from a wellsite surface to a subterranean formation; a drill bit; at least three rotary steerable system (RSS) modules collectively coupled in series between the drill string and the drill bit, wherein each RSS module comprises: at least three steering members spaced circumferentially apart around a perimeter of the RSS module; and a valve operable to sequentially actuate the steering pads; and a controller operable to independently actuate the valve of each RSS module simultaneously.
 7. The apparatus of claim 6 wherein the at least three movable steering pads of each RSS module are disposed at substantially the same axial position.
 8. The apparatus of claim 6 wherein the valve is operable to sequentially actuate the steering pads by sequentially directing fluid to actuators each associated with a corresponding one of the steering pads.
 9. The apparatus of claim 8 wherein the fluid directed to the actuators is received from equipment disposed at the wellsite surface.
 10. The apparatus of claim 6 wherein the controller is operable to actuate the valves of the RSS modules to, simultaneously: sequentially actuate the steering pads of a first one of the RSS modules to operatively urge the first one of the RSS modules in a first azimuthal direction; sequentially actuate the steering pads of a second one of the RSS modules to operatively urge the second one of the RSS modules in a second azimuthal direction substantially different from the first azimuthal direction; and sequentially actuate the steering pads of a third one of the RSS modules to operatively urge the third one of the RSS modules in a third azimuthal direction substantially different from the second azimuthal direction.
 11. The apparatus of claim 10 wherein: the second azimuthal direction is substantially opposite the first azimuthal direction; and the third azimuthal direction is substantially similar to the first azimuthal direction.
 12. The apparatus of claim 11 wherein the first and third azimuthal directions are each angularly offset from the second azimuthal direction by an amount ranging between about 175 degrees and about 185 degrees.
 13. The apparatus of claim 10 wherein the controller is further operable to control the valves of the RSS modules to, simultaneously: actuate the steering pads of the first one of the RSS modules to operatively centralize the first one of the RSS modules within the wellbore; actuate the steering pads of the second one of the RSS modules to operatively centralize the second one of the RSS modules within the wellbore; and sequentially actuate the steering pads of the third one of the RSS modules to operatively urge the third one of the RSS modules away from a longitudinal axis of the first and second ones of the RSS modules.
 14. The apparatus of claim 6 further comprising: a first flexible component flexibly coupling first and second ones of the RSS modules; and a second flexible component flexibly coupling the second one of the RSS modules and a third one of the RSS modules.
 15. The apparatus of claim 6 further comprising: a first joint disposed between first and second ones of the RSS modules; and a second joint disposed between the second one of the RSS modules and a third one of the RSS modules.
 16. The apparatus of claim 6 wherein the drill bit, the at least three RSS modules, and the controller are collectively operable to extend the wellbore with a dogleg of up to twenty degrees per 100 feet (30.5 meters).
 17. A method, comprising: conveying apparatus within a wellbore that extends from a wellsite surface to a subterranean formation, wherein the apparatus comprises a drill string, a drill bit, and at least three rotary steerable system (RSS) modules collectively coupled in series between the drill string and the drill bit, and wherein each RSS module comprises: at least three steering pads spaced circumferentially apart around a perimeter of the RSS module; and a valve operable to sequentially actuate the steering pads; and operating a controller to independently actuate the valve of each RSS module to, simultaneously: sequentially actuate the steering pads of a first one of the RSS modules to operatively urge the first one of the RSS modules in a first azimuthal direction; sequentially actuate the steering pads of a second one of the RSS modules to operatively urge the second one of the RSS modules in a second azimuthal direction substantially different from the first azimuthal direction; and sequentially actuate the steering pads of a third one of the RSS modules to operatively urge the third one of the RSS modules in a third azimuthal direction substantially different from the second azimuthal direction.
 18. The method of claim 17 further comprising operating the controller to control the valves of the RSS modules to, simultaneously: actuate the steering pads of the first one of the RSS modules to operatively centralize the first one of the RSS modules within the wellbore; actuate the steering pads of the second one of the RSS modules to operatively centralize the second one of the RSS modules within the wellbore; and sequentially actuate the steering pads of the third one of the RSS modules to operatively urge the third one of the RSS modules in an azimuthal direction away from a longitudinal axis of the first and second ones of the RSS modules.
 19. The method of claim 17 further comprising, prior to conveying at least a portion of the apparatus within the wellbore, coupling the RSS modules in series between the drill string and the drill bit.
 20. The method of claim 17 further comprising, prior to conveying at least a portion of the apparatus within the wellbore: coupling a first flexible component between first and second ones of the RSS modules; and coupling a second flexible component between the second one of the RSS modules and a third one of the RSS modules. 